Early encounters with a dinosaur can create a lifetime's fascination (Image: Kevin Lamarque/Reuters)

WHAT is the enduring appeal of dinosaurs and fossils? Children have a simple answer – they're neat. The rest of us reach for more varied and complex answers, which mostly boil down to human curiosity. We explore the past for the same reason we explore the environment: to understand the world around us. We may think of the past as immutable because it has already happened, but a lot of it is still unknown.

Those gaps in our knowledge used to be filled with exotic tales of lost worlds and vanished civilisations, where fossils were always relics of legendary events. Dinosaur fossils became mythical dragon bones, while woolly mammoths became "giants in the earth".

Since fossils in general, and dinosaur fossils in particular, are rare and very different from modern animals, it's lucky that humans came wired to spot the unusual, and collect the oddities that resembled ancient life forms long before there was a subject called palaeontology.

In the 21st century, however, the discipline is thoroughly scientific and systematic, with new ways of extracting real and accurate information from old bones and other artefacts of lost worlds.

This exploration is documented in two new books, from different yet complementary viewpoints. In My Beloved Brontosaurus, science writer Brian Switek traces his enthusiasm for dinosaurs back to a childhood visit to the American Museum of Natural History in New York in 1988, when he stood entranced before a giant sauropod fossil. This was labelled Brontosaurus, even though its proper name had been Apatosaurus for several decades. Switek thought that a "thunder lizard" (a translation of brontosaurus) walking "must have sounded like a storm rolling across the Jurassic landscape", he writes, and long after he learned its proper scientific name, Brontosaurus remained his favourite dinosaur.

Switek's writing is crisp and clean, and he knows his dinosaurs. "The old dinosaurs were terribly wrong when I viewed them back in the 1980s," he writes. The old Brontosaurus wore the wrong skull. John Ostrom, the American palaeontologist, and his student Robert Bakker had already launched a dinosaur revival in the 1970s by showing that dinosaurs were active, dynamic creatures, not lethargic tail-draggers like the old Brontosaurus. And the 1996 discovery of the feathered dinosaur Sinosauropteryx thoroughly transformed our vision of the two-legged predatory dinosaurs, such as Velociraptor and Tyrannosaurus rex, that eventually gave rise to birds.

Initially, Switek says, he thought feathered dinosaurs looked silly. "Dinosaurs were supposed to look mean and scabrous. With feathers on, Velociraptor just looked like a big chicken." But the evidence was soon overwhelming – the latest research shows tiny melanin particles coloured the feathers.

Dinosaur feathers provided key support for Ostrom's earlier proposal that birds had evolved from small, swift predatory dinosaurs. The development of feathers also mirrored the development of other features associated with flight, with shorter-armed dinosaurs having short, fuzzy feathers, and full flight feathers appearing on the longer arms of Archaeopteryx and Microraptor. Feathers made the evolutionary trend clear even to those who couldn't tell a femur from a furcula.

Written around his visits to see important fossils, Switek's book is something of a travelogue as well as a chronicle built from years of blogging about dinosaurs. I especially enjoyed his recollection of a visit to the Wyoming Dinosaur Center – a surprisingly dull venue considering that it houses an evolutionary icon, the only Archaeopteryx in the US.

Switek does a good job of keeping up with the latest refinements in dinosaur science. Crucially, he shares his enthusiasm well, writing about the fun, the weird and the wonderful without the tall tales of the explorers of old. He devotes, for example, a whole chapter, entitled "Big Bang Theory", to dinosaur sex. Tests using computer models, he says, show why the traditional male mounting of the female would never have worked for Kentrosaurus, a cousin of Stegosaurus, which has large spikes above its hips. Ouch.

By contrast, Lance Grande's The Lost World of Fossil Lake is a photographic catalogue of wonders, detailing the fossils that accumulated at the bottom of the lake near the intersection of Wyoming, Utah and Colorado some 15 million years after the dinosaurs bit the dust following that famous asteroid impact in Mexico's Yucatan peninsula.

For a few tens of thousands of years – a fleeting moment in geological time – conditions were just right for near-perfect fossilisation. Like the Burgess Shale formation in the Canadian Rockies, famed for its soft-bodied fossils, and the Jehol formation in north-eastern China, known for its feathered dinosaurs, Fossil Lake is a Lagerstätte, a site with extraordinarily diverse or well-preserved fossils.

Being given one of those fossils changed Grande's life as a student at the University of Minnesota in the mid-1970s. "It was a beautiful piece that required little effort to imagine as a living creature," he recalls, and he asked geology professor Robert Sloan to identify it. After a moment's study, Sloan replied: "I won't tell you what this is, but if you take my vertebrate palaeontology course, you will be able to identify it yourself."

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